1. Field of Invention
The present invention relates to a method of transmitting data between controllers, and more particularly to, a system and a method of transmitting data between two controllers of a dual-controller system.
2. Related Art
Usually, a dual-controller system is applied in an environment having a high requirement on the completeness of data and the continuity of service, e.g., a storage area network (SAN). The function of the dual-controller system lies in that, when one of the controllers is taken as a server, i.e., when the main server is providing a service, the other controller is taken as a mirror backup server of the main server. Therefore, when the main server is down and cannot continue to provide services, the backup server takes over the services of the main server, so as to ensure the completeness of data and the continuity of services.
Therefore, it is necessary to establish an internal communication link between the two controllers of the dual-controller system, e.g., Ethernet card interconnection, for transmitting data, so as to keep the synchronization of the two controllers. Sometimes, a plurality of links for providing the internal communication mechanism may exist in the dual-control system at the same time, e.g., an optical fiber interface or an Ethernet interface etc. However, due to the differences of the transmission media and protocol standards of the links, the performances of transmitting different types of data packets are different. For example, communication links having high transmission frequencies but small maximum transmission units are suitable for transmitting data packets of a small scale. On the other hand, the performance of communication links having low transmission frequencies but large maximum transmission units is obvious during the transmission of large block data.
Therefore, the conventional internal communication link of a single path is limited by the transmission medium, and is only suitable for the data in a certain data packet scale range. Once a data packet exceeding the range is transmitted, the performance will be reduced. Moreover, when the scale of the transmitted data keeps changing, the transmitting performance will greatly fluctuate correspondingly.